Question: $-\dfrac{9}{12} + \dfrac{9}{8} = {?}$
Explanation: $ = - {\dfrac{9 \times 2}{12 \times 2}} + {\dfrac{9 \times 3}{8 \times 3}} $ $ = - {\dfrac{18}{24}} + {\dfrac{27}{24}} $ $ = - \dfrac{{18} + {27}}{24} $ $ = \dfrac{9}{24}$